U.S. patent application number 10/825807 was filed with the patent office on 2004-12-09 for sync signal insertion/detection method and apparatus for synchronization between audio file and text.
Invention is credited to Kim, Nam-Hoon, Lee, Won-Ha, Shin, Seung-Won.
Application Number | 20040249862 10/825807 |
Document ID | / |
Family ID | 33475973 |
Filed Date | 2004-12-09 |
United States Patent
Application |
20040249862 |
Kind Code |
A1 |
Shin, Seung-Won ; et
al. |
December 9, 2004 |
Sync signal insertion/detection method and apparatus for
synchronization between audio file and text
Abstract
A method for inserting sync signal which can be outputted in
synchronization with the text into audio file s while playing audio
files, and apparatus thereof are disclosed. First, information of a
size of the first part of the frame is obtained from the second
part of the frame. Then, based on the obtained information, a start
position and a size of the third part of the frame is determined,
and at least a part of the sync signal is inserted into the third
part of the frame. Therefore, a sync signal can be effectively
inserted into audio files without damaging the contents of the
audio file.
Inventors: |
Shin, Seung-Won; (Seoul,
KR) ; Lee, Won-Ha; (Seoul, KR) ; Kim,
Nam-Hoon; (Anyang-si, KR) |
Correspondence
Address: |
TRANSPACIFIC LAW GROUP
617 NORTH DELAWARE STREET
SAN MATEO
CA
94401
US
|
Family ID: |
33475973 |
Appl. No.: |
10/825807 |
Filed: |
April 16, 2004 |
Current U.S.
Class: |
1/1 ;
704/E21.019; 707/999.107 |
Current CPC
Class: |
G10L 21/06 20130101 |
Class at
Publication: |
707/104.1 |
International
Class: |
G06F 017/00 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 17, 2003 |
KR |
2003-0024306 |
Claims
What is claimed is:
1. A method of inserting sync signal into audio file containing a
plurality of frames, each frame includes a first part in which
audio contents are stored, a second part which contains at least
information of a size of the first part, and a third part which
text and sync signal can be inserted into and is within the first
part, comprising: (a) obtaining information of a size of the first
part of the frame from the second part of the frame; (b)
determining a start position and a size of the third part of the
frame based on the obtained information; and (c) inserting at least
a part of the sync signal into the third part of the frame.
2. The method according to claim 1, wherein the first part contains
the audio contents, the second part contains header information of
the audio file, and the third part is a part which is within the
first part and least affects the sound quality while playing audio
file.
3. The method according to claim 1, wherein the third part contains
an area which presents whether the sync signal exists, and an area
which presents contents of the sync signal.
4. The method according to claim 1, wherein the sync signal
contains information of a position of a text which corresponds to
the first part of the frame.
5. The method according to claim 1, wherein said step (c)
comprises: deciding whether to insert the sync signal into the
third part; and inserting text information which corresponds to the
first part of the frame into the third part of the frame, in
response to the decision of not inserting the sync signal.
6. The method according to any one of claims 1 to 5, wherein said
step (c) comprises: comparing the sync signal inserting space in
the third part with the size of the sync signal, and in case that
the sync signal inserting space in the third part is smaller than
the size of the sync signal, inserting a part of the sync signal
into the third part wherein the part of the sync signal has an
equivalent size to the sync signal inserting space.
7. The method according to claim 1, wherein the audio contents are
produced by TTS (Text-to-Speech) transformation of the text.
8. A method of detecting sync signal from an audio file containing
a plurality of frames, each frame includes a first part in which
audio contents are stored, a second part which contains at least
information of a size of the first part, and a third part which
text and sync signal can be inserted into and is within the first
part, comprising: extracting information of a start position and a
size of the third part based on the information of the size of the
first part; analyzing the third part to decide whether the sync
signal exists; and obtaining at least a part of the sync signal
from the third part, in response to the decision that the sync
signal exists.
9. The method according to claim 8, wherein the first part contains
the audio contents, the second part contains header information of
the audio file, and the third part is a part which is not used in
playing the audio contents of the audio file.
10. The method according to claim 8, wherein the third part
contains an area which presents whether the sync signal exists, and
an area which presents contents of the sync signal.
11. The method according to claim 8, further comprising: extracting
text information from the third part, in response to the decision
that the sync signal does not exist.
12. The method according to claim 8, further comprising: analyzing
contents of the sync signal, and thereafter constituting text
information corresponding text based on the analysis.
13. The method according to any one of claims 8 to 12, further
comprising: combining at least a part of the sync signal with at
least a part of the sync signal of the subsequent frame, in case
that at least a part of the sync signal obtained from the third
part is not the same as the sync signal.
14. An apparatus for detecting a sync signal from an audio file
containing a plurality of frames, each frame includes a first part
in which audio contents are stored, a second part which contains at
least information of a size of the first part, and a third part
which text and sync signal can be inserted into and is within the
first part, comprising: a decision portion of extracting
information of a start position and a size of the third part based
on information of the size of the first part, and deciding whether
the sync signal exists by analyzing the third part; and a sync
signal obtaining portion of obtaining at least a part of the sync
signal from the third part, in response to the decision that the
sync signal exists.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a method for synchronizing
digital audio files and texts corresponding thereto in a portable
digital playback device and apparatus thereof.
[0003] 2. Description of the Related Art
[0004] Recently, in accordance with the development of computer
technology, the technology for playing audio files by using a
computer is rapidly developing. In this regard, a function of
playing audio files simultaneously with visually indicating details
of audio files is attracting attention. For instance, at the same
time of playing audio files related to songs, the technology for
indicating lyrics of such songs on screen corresponds to such
technology.
[0005] Referring to FIG. 10, a constitution to simultaneously
indicate details of contents while playing audio files in prior art
is described hereinbelow.
[0006] First, audio files which are subjects for playing and a text
file which stores details of audio files are prepared. FIG. 10 is a
drawing re-constituting the conventional text file that stores
details of audio file in a format of a table. In FIG. 10, the text
file is storing not only details of audio files but also a playback
point which indicates details of audio files visually. In the
embodiment of FIG. 10, during playback of a compressed voice or a
music file, a playback point notifying the time for outputting text
is stored in a unit of {fraction (1/1000)} second.
[0007] For instance, at the playback point of 0000040 ms, audio
files are played, and a row of characters "IN A PORTABLE DIGITAL
PLAYBACK DEVICE," corresponding to such audio files is outputted
visually through a predetermined display. As audio files are being
played, at the playback point of 0001055 ms, a row of characters
"WHILE PLAYING MUSIC OR VOICE FILES," is outputted simultaneously
with the playback of audio files.
[0008] That is, the playback point is watched while playing audio
files, and if the playback point is consistent with the playback
point of the outputted row of characters indicated in the table,
the outputted row of characters is outputted.
[0009] The structure of the text file such as above is, for
instance, substantially similar to the structure of ".smi file" for
outputting caption in the moving pictures, which is a structure
suitable for a case wherein usable resources such as a computer are
sufficiently provided.
[0010] However, if digital audio files and texts corresponding
thereto are synchronized in a portable digital playback device with
the aforesaid method, the usable resources are limited.
Accordingly, it is realistically not possible for the portable
digital playback device to watch the playback point of ms unit of
audio files, and thus to output texts so as to be consistent with
such fine playback point. Due to such impossibility, the aforesaid
method wherein the playback point and texts are stored in a text
file in a format of a table and texts are outputted based on the
information of the table is not suitable to the portable digital
playback device.
[0011] Moreover, since the conventional text outputting method
outputs the text information arbitrarily on the liquid crystal
screen according to the time played, a problem arises wherein the
contents actually played and contents outputted on liquid crystal
screen are not consistent to each other.
[0012] Next, a method for inserting sync signal into digital audio
files as a watermark by the frequency transform etc. is described
hereinbelow. Generally, a watermarking technology refers to a
technology for storing information of works unrecognizable by
ordinary people in a sound source in order to protect copyright,
and to determine whether alteration/forgery is made on copyright
works, etc. As the watermarking technology hides information
defined by a user in the substantial sound source of the copyright
work, it is common to use a robust watermark having characteristics
wherein said watermark is strong against signal process attacks,
compression transformation, etc. and is difficult to remove said
watermark with ill intention.
[0013] Such watermarking inserts data in the sound source of the
digital content, and thus a considerably complicated operation
should be carried out in order to detect hidden information again,
which accompanies a large amount of memories and calculations. In
order to realize the watermarking technology with the ordinary DSP,
a considerable amount of resources is consumed and thus a problem
arises in which it is difficult to use the watermarking technology
to a portable digital playback device such as a portable MP3 player
using DSP. Further, additional functions which consume a large
amount of resources are not preferable in view of the limited hours
of battery duration of the portable playback device. Particularly,
since most of the audio data are formatted compressing the subject
files, the ordinary watermarking technology is not usable.
[0014] A technology for hiding information in the compressed data
is disclosed in MP3Stego (Computer Laboratory, Cambridge, August,
1998) suggested by F. Petitcolas. This technology hides data during
the process of compressing sound source, and thus a problem arises
in which a high speed insertion process is not possible.
[0015] Also, Non-Invertible Watermarking Methods For MPEG Encoded
Audio (Security and Watermarking of Multimedia Contents, January
1999) suggested by L. Qia and K. Nahrstedt include a high concern
for degrading sound source of MP3, and there is a problem of
limited amount of information which can be hidden.
[0016] Further, a compressed-domain watermarking algorithm for MPEG
Audio Layer3 (ACM Multimedia 2001, September 30-October 5, Ottawa,
Ontario, Canada) suggested by D. K. Koukopoulos and Y. C. Stamatiou
is capable of high speed extraction, but there is a problem in
which high speed insertion process can not be carried out.
SUMMARY OF THE INVENTION
[0017] The present invention is contrived to solve the above
mentioned problems, and its object is to provide a sync signal
insertion method of inserting text and the sync signal into an
audio file in order to minimize the effect of text synchronization
made upon quality of sound, to enable high speed insertion/process
while making the playback point of the audio files consistent with
the output point of the text such that audio files and text can be
synchronized.
[0018] Moreover, another object of the present invention is to
provide a method which does not generate excessive resource
consumption to the audio files playback device when playing audio
files and outputting contents which have been synchronized together
therewith.
[0019] Also, another object of the present invention is to provide
a sync signal detection method and an apparatus for detecting the
sync signal from the audio file in which the sync signal has been
inserted.
[0020] In order to achieve the aforementioned objects, the present
invention provides a method of inserting sync signal into audio
file containing a plurality of frames, each frame includes a first
part in which audio contents are stored, a second part which
contains at least information of a size of the first part, and a
third part which hardly affects the sound quality after being
inserted by the text and the sync signal, comprising steps of
obtaining information of a size of the first part of the frame from
the second part of the frame; determining a start position and a
size of the third part of the frame based on the obtained
information; and inserting at least a part of the sync signal into
the third part of the frame.
[0021] Herein, the first part contains audio contents, the second
part contains header information and side information of the audio
file, and the third part is a part which hardly affects the sound
quality after being inserted by the text and the sync signal in the
audio data. Also, the third part contains an area which presents
whether the sync signal exists, and an area which presents contents
of the sync signal.
[0022] Further, the sync signal may contain information of a
position of a text which corresponds to the first part of the
frame, and the step of inserting at least a part of the sync signal
into the third part of the frame comprises steps of deciding
whether to insert the sync signal into the third part; and
inserting text information which corresponds to the first part of
the frame into the third part of the frame in response to the
decision of not inserting the sync signal.
[0023] Also, it is preferable for the step of inserting at least a
part of the sync signal into the third part of the frame to
comprise steps of comparing the sync signal inserting space in the
third part with the size of the sync signal, and in case that the
sync signal inserting space in the third part is smaller than the
size of the sync signal, inserting a part of the sync signal into
the third part wherein the part of the sync signal has an
equivalent size to the sync signal inserting space.
[0024] Further, the audio files may be produced by TTS
(Text-to-Speech) transformation of the text.
[0025] Meanwhile, the present invention provides a method of
detecting sync signal from an audio file containing a plurality of
frames, each frame includes a first part in which audio contents
are stored, a second part which contains at least information of a
size of the first part, and a third part which text and sync signal
can be inserted into and is within the first part, comprising steps
of extracting information of a start position and a size of the
third part based on the information of the size of the first part;
analyzing the third part to decide whether the sync signal exists;
and obtaining at least a part of the sync signal from the third
part in response to the decision that the sync signal exists.
[0026] Herein, the first part contains audio contents, the second
part contains header information of the audio file, and the third
part is a part which is not used in playing the audio contents of
the audio file. Also, the third part contains an area which
presents whether the sync signal exists, and an area which presents
contents of the sync signal.
[0027] Also, in response to the decision that the sync signal does
not exist, the method (of detecting sync signal from an audio file
containing a plurality of frames) may further comprise a step of
extracting text information from the third part. After analyzing
contents of the sync signal, the method may further comprise a step
of selecting a position of the corresponding text based on the
analysis.
[0028] Further, it is preferable for the method to further comprise
a step of combining at least a part of the sync signal with at
least a part of the sync signal of the subsequent frame, in case
that at least a part of the sync signal obtained from the third
part is not the same as the sync signal.
[0029] Meanwhile, the present invention provides an apparatus for
detecting a sync signal from an audio file containing a plurality
of frames, each frame includes a first part in which audio contents
are stored, a second part which contains at least size information
of the first part, and a third part which text and sync signal can
be inserted into and is within the first part, comprising a
decision portion of extracting information of a start position and
a size of the third part based on information of the size of the
first part, and deciding whether the sync signal exists by
analyzing the third part; and a sync signal obtaining portion of
obtaining at least a part of the sync signal from the third part in
response to the decision that the sync signal exists.
BRIEF DESCRIPTION OF THE DRAWINGS
[0030] FIG. 1 is a conceptual diagram illustrating overall process
for synchronizing audio files and texts corresponding thereto in
the portable digital playback device;
[0031] FIG. 2 is a drawing showing the structure of the MP3
frame;
[0032] FIG. 3 is a flow diagram showing a sync signal insertion
process according the first embodiment of the present
invention;
[0033] FIG. 4 is a flow diagram showing a sync signal insertion
process according to the second embodiment of the present
invention;
[0034] FIG. 5 is a schematic diagram illustrating audio files
inserted with a sync signal according to the second embodiment of
the present invention in a unit of a frame;
[0035] FIG. 6 is a conceptual diagram illustrating a process for
synchronizing audio files and texts generated with a TTS
technology;
[0036] FIG. 7 is a schematic diagram schematically explaining the
process of detecting the sync signal according to the present
invention.
[0037] FIG. 8 is a block diagram showing the inside with regard to
a case wherein a sync signal detection device for synchronizing
texts according to the present invention is realized on DSP of the
portable digital playback device;
[0038] FIG. 9 is a block diagram showing the inside with regard to
realization of DSP of the portable digital playback device; and
[0039] FIG. 10 is a drawing re-constituting the conventional text
files which store details of audio files in a form of a table.
DETAILED DESCRIPTION
[0040] Embodiments of the present invention will be described in
detail with reference to the drawings in the following.
[0041] FIG. 1 is a conceptual diagram illustrating overall process
for synchronizing audio files and texts corresponding thereto in
the portable digital playback device.
[0042] Referring to FIG. 1, first, audio file 103 and the text 101
corresponding thereto are inputted to a text synchronization device
150. By using the inputted information, users directly input the
point of time each of lyrics is to be outputted in the text
synchronization device 105. Information inputted by users may be
constituted with text to be outputted and information connected to
the playback time, respectively. The text synchronization device
105, according to the sync signal insertion method of the present
invention, inserts text data and output point for outputting text
corresponding to a predetermined position of the audio file
103.
[0043] Thereafter, in a case wherein the portable playback device
109 plays the audio file 103, if the sync signal is detected during
the audio file playback, such sync signal is analyzed, text data is
searched according to the sync signal, and the searched row of
characters is outputted by a display means of the portable playback
device 109.
[0044] Hereinbelow, the embodiment of the present invention
describes the format of the music file as MP3. However, in a case
of music files stored according to other different audio file
formats such as WMA, AAC, AC3, etc., it is obvious for the one
skilled in the art to adapt or apply the sync signal insertion
method of the present invention to those files.
[0045] FIG. 2 is a drawing showing the structure of the MP3 frame.
Referring to FIG. 2 to explain the structure of the MP3 frame, MP3
audio file is constituted with a series of plurality of frames, and
each frame includes a header 201 comprising 12 bits of synchronized
bits, side information 203, main data 205, and a stuffing space
207.
[0046] The header 201 and the side information 203 store the
overall information concerning the structure of the frame, etc.
including sync. The main data 205 compresses and stores audio
contents without any loss according to the Huffman Coding method.
The compressed main data 205 without any loss is to be stored in a
unit of a bit, and as a result of the Huffman Coding, surplus bits
which do not include the audio contents at all are generated. Such
surplus bits are called stuffing bits, if stuffing bits are used,
text data can be inserted without affecting the sound quality.
Although the size of stuffing bits depends on the compressing
method, stuffing bits are not large enough to contain all the text
data in MP3, so it is not possible to insert the text information
only by using the stuffing bits.
[0047] So, it is desirable to analyze main data (205), search the
data region which least affects the sound quality, and to use the
region as a text hiding place. The space which least affect the
sound quality is high-frequency region among main data (205), and
it is possible to insert text data in this data region. The part
which hardly affects the sound quality among the main data and
represents high-frequency band signal is called watermark space
(207), and data is inserted by using the watermark space (207).
[0048] Hereinbelow, as set forth in more details, the present
invention uses the constitutional characteristics of the frame and
inserts sync signals in the watermark space.
[0049] FIG. 3 is a flow diagram showing a sync signal insertion
process according to the first embodiment of the present invention.
Referring to FIG. 3, first, if the MP3 audio file to be played is
selected, such file is divided into a unit of a frame (S301).
[0050] With regard to each of the divided frame, a frame analysis
is performed (S303). The frame analysis analyzes the header 201 and
the side information 203 so as to obtain information concerning the
starting position of the main data 205 and information concerning
its size. Thereafter, based on the information concerning the size
of the main data 205, the size and the position of the watermark
space 207 are obtained. Watermark space 207 is a data convertible
region within the remaining bits of the frame and high-frequency
representing region.
[0051] Thereafter, it is determined whether the sync signal should
be inserted in the pertinent frame (S311). Determining whether the
sync signal is inserted may be considered according to the
information previously inputted by the user. For instance, the user
may directly input information for outputting which portion of the
text at which point of time through a predetermined input device of
the text synchronization device while playing the audio file. Also,
similar to a case adopting a TTS method mentioned later, it may be
automatically determined. In a case wherein the sync signal is to
be inserted, the sync signal is inserted in the stuffing space
(S313). Since the size of the sync signal is generally bigger than
the number of bits of the stuffing space, the entire one sync
signal is not inserted into one stuffing space, but at least
portion of the sync signal is inserted into one stuffing space. One
sync signal may be inserted into a plurality of stuffing spaces. In
the exemplary embodiment, the stuffing space includes a part
indicating existence of the sync signal, and a part indicating the
position of the text as the contents of the sync signal and the
number of characters of the text to be outputted. Determining how
many bits of the sync signals are inserted in the pertinent frame
depends on how many bits the provided stuffing space have.
[0052] By repeating the aforementioned process with regard to each
frame, the sync signals are inserted into audio files comprised of
frames.
[0053] Hence, through the aforementioned constitution, by providing
sync signals which are inserted in the audio file in order to
synchronize the audio files and texts, at the time of playing audio
files and outputting texts synchronized therewith, an excessive
resource consumption will not occur in the audio files playback
device.
[0054] Next, referring to FIGS. 4 & 5, the second embodiment of
the present invention is described. FIG. 4 is a flow diagram
showing a sync signal insertion process according to the second
embodiment of the present invention.
[0055] Although not illustrated in FIG. 4, Steps of S301 to S309 of
FIG. 3 are identically included prior to S411 of FIG. 4.
Illustration and explanation thereof will be omitted for
convenience.
[0056] First of all, whether it is necessary to insert sync signals
will be determined (S411).
[0057] If it is not necessary to insert sync signals, texts are
inserted in the watermark space (S415). Since the length of the row
of characters of texts is generally longer than the number of bits
in the watermark space, the entire row of characters of the given
texts is not inserted in a single watermark space, but at least a
part of the row of text characters is inserted in a single
watermark space. That is, a plurality of watermark spaces is
inserted with a single row of text characters.
[0058] FIG. 5 is a schematic diagram illustrating audio files in
which sync signal is inserted in accordance with the second
embodiment of the present invention in a unit of frames. In FIG. 5,
audio files are schematically illustrated by being segmented in a
unit of frames. Regarding each frame, the frame corresponding to
text information insertion includes text information and the frame
corresponding to text output point includes sync signal. The frame
corresponding to text information insertion may not include any
inserted information at all in the stuffing space, and as described
above, this means a waiting zone. First, the text information to be
outputted is inserted into one or more frames so that the playback
point of the frame including a sync signal becomes the point
outputting the text already inserted in the previous frame. After
all of the text information to be outputted is inserted, the frame
stays in a waiting status until a sync signal is inserted. In the
waiting status, no separate information is inserted into the frame
and all of the stuffing bits existing in each frame are initialized
to `0`. Then, if the position of the present frame becomes
consistent with the time information of the text to be outputted,
the sync signal is inserted.
[0059] Now, back to FIG. 4, if a sync signal is to be inserted, the
sync signal should be inserted into the watermark space (S413). As
described above referring to FIG. 3, since the size of a sync
signal is generally larger than the number of bits of a watermark
space, not only can the entire sync signal be inserted in one
watermark space, but also at least a part of the sync signal can be
inserted in one watermark space. That is, one sync signal can be
inserted in a plurality of watermark spaces. It is sufficient for
the sync signal to be inserted in the watermark space only to
include the part indicating the existence of the sync signal. This
is because when playing the audio file, since the information
stored in the watermark space of the previous frames of the frame
wherein the sync signal is detected are fragments of text
information, if they are collected, the text to be outputted by the
display can be obtained when detecting whether the sync signal
exists.
[0060] By repeating the above process for each frame, the sync
signal and text corresponding to the audio file is inserted into
the audio file comprised of frames.
[0061] Meanwhile, the process of synchronizing audio files and
lyric texts in accordance with the present invention may be
obtained by using the TTS (Text-to-Speech) engine. FIG. 6 is a
conceptual diagram illustrating a process of synchronizing voice
files and texts produced by the TTS technology.
[0062] TTS is a technology for transforming texts into voice files
by voice synthesis. When transforming text characters into audio
files, the TTS engine 603 establishes a phoneme DB of the smallest
phonetic unit of the language of each country. Then considering the
context of the text characters, the searched phoneme DBs are
synthesized to generate a voice signal. In the description of the
constitution of the present invention referring to FIG. 1, the
location of the audio file and the text to be synchronized must be
directly inputted by the user. However, as for voice synthesis by
TTS, the location of the text in the corresponding text file can be
automatically located at the same time of producing a voice file,
and thus no separate user input process is required.
[0063] The process of detecting the sync signal in accordance with
the present invention will be described in the following.
[0064] FIG. 7 is a schematic diagram schematically illustrating the
process of detecting the sync signal in accordance with the present
invention.
[0065] MP3 audio files are stored in the memory. Information on the
MP3 audio files is read from the memory in response to the playback
instructions of the MP3 audio file (S701). The read MP3 audio files
are provided in a form of MP3 stream in order to analyze the
frame.
[0066] Then, the audio files transmitted in the form of MP3 stream
are segmented into a unit of frames (S703).
[0067] Then, Watermark information bit identifier extracts size of
audio contents by using header and side information for each frame.
Based on the size of audio contents, it is possible to know the
position of value representing optimal high-frequency band signal
and position of stuffing bits. Then, if the watermark is inserted,
detected information and bit size of the information is transferred
to sync signal and text constitutor.
[0068] Then, the contents of the detected sync signal are analyzed
to constitute a sync signal and text (S707). In the first
embodiment, the location of the text in the text files indicated by
the sync signal and the length of the row of characters to be
presented are determined, and thus the corresponding row of
characters is read from the text file. Meanwhile, as for the second
embodiment wherein the text is included in the MP3 audio file, if a
sync signal does not exist, the contents of the watermark space 207
is read, and then continuously stored in a separate memory space.
If a sync signal is detected, the contents stored in the memory
space are outputted as a text. After being outputted as a text,
said contents are removed from the memory space. Then, the row of
characters comprising text is provided to be displayed on an
LCD.
[0069] Then, the LCD controller (not shown) controls the LCD so
that the row of characters currently displayed on the LCD is
deleted and a new row of characters is displayed (S709). In this
case, if a text longer than the row of characters which can be
simultaneously displayed on an LCD is to be outputted, the row of
characters can be automatically scrolled from the right to the
left, and such scrolling process is known to the one skilled in the
art.
[0070] The sync signal detector of FIG. 7 can be realized at a
portable digital playback device as shown in FIGS. 8 & 9. In
general, it is realized in a DSP, however since the MICOM controls
all external devices for text synchronization, if there is enough
resource left in the MICOM, it is preferable to be realized at the
MICOM as shown in FIG. 8. When realizing synchronization using the
method proposed in the present invention, less time and memory are
to be spend, and thus it can be easily realized at a MICOM.
[0071] FIG. 8 is a block diagram showing the inside with regard to
a case wherein a sync signal detection device for synchronizing
texts in accordance with the present invention is realized on DSP
of the portable digital playback device; and FIG. 9 is a block
diagram showing the inside with regard to realization of DSP of the
portable digital playback device.
[0072] FIGS. 8 & 9 are block diagrams showing the inside of
ordinary playback devices wherein the name of the file to be played
is brought from the MICOM when the user presses the play button.
After bringing the name of the file to be played, the data of said
file is read and transmitted to the buffer. In the DSP, the data
compressed in the buffer are decoded, and music is played through
the speaker.
[0073] If the present invention displaying lyrics or voice
information of files to be played on the LCD is inserted into this
process, its entire structure is changed as the following. The
process of bringing the file to be played at the MICOM is the same.
After bringing the file to be played, the data read from the played
file is transmitted to the buffer, and the sync signal detector
searches whether there is a sync signal in the transmitted data. At
this time, if a sync signal is detected at the sync signal
detector, the controller of the MICOM informs that the sync signal
is found and what the contents of the sync signal that is found is.
At the LCD controller of the MICOM, the information received from
the sync signal detector is displayed on the LCD.
[0074] The difference between FIG. 8 and FIG. 9 is only where the
sync signal detector is located. However, the entire prosecution is
the same regardless of which form it takes to serve the
constitutional characteristics of the portable playback device.
[0075] The present invention is described with reference to
specific embodiments regarding specific applications. A person
having ordinary skill in the art may make additional modifications,
applications and embodiments within the scope of the present
invention.
[0076] Therefore, the following claims are recited to cover all
applications, modifications and embodiments within the scope of the
present invention.
[0077] The present invention provides a function which can display
music lyrics or voice contents which are automatically played on
the LCD when playing music files or voice files by adding a text
synchronization device to the portable digital playback device.
[0078] The present invention detects the sync signal hidden in
music files during the compressed files being played in real-time,
and displays in synchronization with the point at which the
contents file currently being played on an LCD. Therefore, the user
can confirm the contents currently being played through the LCD of
the playing device. Also, by hiding all information in digital
content until the text information and the text are outputted, the
user does not have to store the text file or other information
separately.
[0079] In particular, since the present invention can be widely
applied from ordinary music lyrics to teaching materials for
studying foreign languages, it can be effectively used in portable
digital playback devices used for language study.
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